Start the computer from an MS-DOS floppy disk that contains the Sys.com file. Sys the boot drive to MS-DOS by typing the following command at a command prompt:
a:\>sys c:
After you type this command, you receive a system transferred message when the procedure is finished.

NOTE: This command disables the Windows boot loader so that the computer boots MS-DOS when booting from the computer's hard disk. You must repair the Windows boot loader after you use the following steps.

Reboot the computer from the computer's hard disk to a command prompt and install MS-DOS on the computer if it is not already installed.

After you completely install MS-DOS and reboot, restart your computer by using the Windows Setup disks. During Setup, select R to repair Windows.

NOTE: You need to repair only the Windows boot sector. Do not choose to inspect the registry files, the Windows system files, or the Windows boot environment during this procedure.

After you repair the Windows boot sector, you need to manually edit the Boot.ini file to include an option to boot to MS-DOS. The Boot.ini file is a read-only, hidden, system file that is located in the root folder of the boot drive. Add the following line to the Boot.ini file under the operating systems section:c:\="Microsoft DOS".